1st time my 10 player raid did this we only had 2 ranged as well. A mage and my hunter... we got the achievement to have no parasites reach any player on our 1st kill.
Our tactic was to have our DK tank place his death and decay on top of the pillar of flame where the adds come from... I put my frost trap down on the pillar of flame and misdirected to our DK with multishot. The DK just ran round the outside of the trap. I can't remember specifically what our mage did or even what spec he was but we aoe'd them all down without any problem.
You have a very different setup but you can certainly do it with what you have. What Lollis said sounds a viable solution for you.
tell your mage to reroll fire and your dk to go frost and you can basicly kill the adds in 10seconds. Also it's hardly needed to bring 2 tanks and 3 healers. My raid does it with 1 tank 2 healers (we get 2x moonkin to do tranquility at seperate times right after adds spawn.)
Our setup is.
Pala tank
Arms warrior (tank offspec)
Frost DK
2X moonkin
Holy pala
Holy priest
Survival hunter
Elem shammy
Fire mage
Adds go down so fast. as you said you got 2 ranged, get your dk to go frost and your mage to go fire and you should be able to kill adds fast.
Tell whoever of your tanks with the best dps gear to go and only dps boss since warrior and ret pala dps isnt the best for aoe.
Also your restodruid should go moonkin so you got atleast 1 decent knockback.
In 25's we ignore the adds, stick our warrior tank on them he uses stun rotation and kills them solo whilst the rest of he raid gets the easy job of killing the boss.
As a protection warrior you can easily tank all of the parasites. You only need a few heals in the beginning but when you get your first Victory Rush it's not a problem anymore and in the end you'll be pulling 4-5k hps as a warrior which is pretty insane. If you want to feel extra safe put in the Glyph to heal for 50% more. Just make sure you aoe them like crazy to keep the VR procs rolling.